It is known that, upon a landing, an airplane loses in altitude and reduces its speed for switching from cruising flight conditions to landing conditions. During its descent, the airplane takes various aerodynamic configurations. Upon a cruising flight, the external surface of the airplane is the smoothest possible. When it is coming close to the ground, various steps are provided, during which the flaps and slats are opened. Usually, an airplane comprises at least three distinct opening configurations for the flaps and slats.
Moreover, upon the approach, the airplane generally follows a vertical profile including altitude levels, during which decelerations are performed.
In order to decrease the sound nuisance upon a landing, it is known to perform a Continuous Descent Operations (“CDO”) approach type. Such an approach does not include any deceleration level at a constant altitude, but the airplane decelerates in the same time it is descending, and the descent is calculated so as to intercept a descent aligning segment of the airport, without any level.
A CDO type approach thus consists in eliminating the usual levels so as to enable the airplane to fly higher and with weaker thrust levels.
Presently, such approach type is only validated and implemented for weak traffic densities.
The object of the present invention is to aim at implementing such concept upon denser traffic periods, without for all that degrading capacity and safety.
The method usually used by the air control centre to manage the separation between airplanes is the so-called vectoring, which corresponds to using heading and/or speed instructions. With this end in view, in the framework of the air traffic, a new aiding function for the airplane separation is developed so as to come closer to the theoretical Terminal Maneuver Area (“TMA”) capacity, the so-called function Airborne Separation Assistance System Spacing Sequencing and Merging (“ASPA S&M”).
The object of the function ASPA M&S is to improve the capacity and regularity of the air traffic by decreasing the work load of the controller without increasing the one of the crew. To reach such objective, an airplane must obtain a time separation instruction behind another airplane, a so-called leader airplane, and hold such time separation automatically with a fixed tolerance. Data enabling to determine a target speed being necessary for the guidance are transmitted to the separation aiding system. Such target speed is then used for performing the guidance. Such data being used to calculate the speed adjustment must be memorized, as the object is to be on each past position of the leader airplane with a time offset equal to the separation being required.
The implementation of such a function ASPA S&M presents an acquisition phase, during which the separation required relative to the leader airplane is acquired, this separation being then to be held after the acquisition thereof. In order to hold such separation, the position, the speed and the acceleration of the follower airplane and the leader airplane are linked by a dynamic law. Such maneuver thus consists in acquiring and then holding a time separation (at the latest at the end of a given duration or at the latest on a given point, according to the maneuver instructed by the controller), and holding it within a given tolerance by acting on the speed while following the flight plan.
The disadvantage of such a function ASPA S&M is that it involves for the follower airplane (if the performances thereof are different from those of the leader airplane) go-around thrusts and the height and speed profile being left, which has been optimized by the flight management system of the Flight Management System (“FMS”) type as a function of the airplane performances, of forgotten constraints and of weather forecast. Thus, the optimized initial profile of the follower airplane (such as calculated by the system FMS) is degraded due to the constraints generated by the follow-up of the leader airplane.
Moreover, some limitations are predicted for the implementation of a function ASPA S&M, requiring specifically:                aircrafts with similar performances;        identical side flight plans; and        an autopilot and an auto-throttle engaged.        
The implementation of such a function can thus lead to negative environmental impacts for an isolated flight.
The invention has as an object to define an adaptive vertical profile so as to limit the impacts of the function ASPA S&M and thus enable a use of a CDO type approach upon a dense traffic.
The present invention more particularly relates to an aiding method for piloting an aircraft, including a transport airplane, upon an intermediate approach phase of a descent of the aircraft, enabling to remedy the above mentioned disadvantages.